Detection Of Surface Acoustic Waves Research Articles

Prediction of breast cancer risk with volatile biomarkers in breath.

Human breath contains volatile organic compounds (VOCs) that are biomarkers of breast cancer. We investigated the positive and negative predictive values (PPV and NPV) of breath VOC biomarkers as indicators of breast cancer risk. We employed ultra-clean breath collection balloons to collect breath samples from 54 women with biopsy-proven breast cancer and 124 cancer-free controls. Breath VOCs were analyzed with gas chromatography (GC) combined with either mass spectrometry (GC MS) or surface acoustic wave detection (GC SAW). Chromatograms were randomly assigned to a training set or a validation set. Monte Carlo analysis identified significant breath VOC biomarkers of breast cancer in the training set, and these biomarkers were incorporated into a multivariate algorithm to predict disease in the validation set. In the unsplit dataset, the predictive algorithms generated discriminant function (DF) values that varied with sensitivity, specificity, PPV and NPV. Using GC MS, test accuracy = 90% (area under curve of receiver operating characteristic in unsplit dataset) and cross-validated accuracy = 77%. Using GC SAW, test accuracy = 86% and cross-validated accuracy = 74%. With both assays, a low DF value was associated with a low risk of breast cancer (NPV > 99.9%). A high DF value was associated with a high risk of breast cancer and PPV rising to 100%. Analysis of breath VOC samples collected with ultra-clean balloons detected biomarkers that accurately predicted risk of breast cancer.

Picosecond ultrasonic study of surface acoustic waves on periodically patterned layered nanostructures

We have used the ultrafast pump–probe technique known as picosecond ultrasonics to generate and detect surface acoustic waves on a structure consisting of nanoscale Al lines on SiO2 on Si. We report results from ten samples with varying pitch (1000–140 nm) and SiO2 film thickness (112 nm or 60 nm), and compare our results to an isotropic elastic calculation and a coarse-grained molecular dynamics simulation. In all cases we are able to detect and identify a Rayleigh-like surface acoustic wave with wavelength equal to the pitch of the lines and frequency in the range of 5–24 GHz. In some samples, we are able to detect additional, higher frequency surface acoustic waves or independent modes of the Al lines with frequencies close to 50 GHz. We also describe the effects of probe beam polarization on the measurement’s sensitivity to the different surface modes.

Qubit-Assisted Transduction for a Detection of Surface Acoustic Waves near the Quantum Limit.

We demonstrate ultrasensitive measurement of fluctuations in a surface-acoustic-wave (SAW) resonator using a hybrid quantum system consisting of the SAW resonator, a microwave (MW) resonator, and a superconducting qubit. The nonlinearity of the driven qubit induces parametric coupling, which up-converts the excitation in the SAW resonator to that in the MW resonator. Thermal fluctuations of the SAW resonator near the quantum limit are observed in the noise spectroscopy in the MW domain.

Attenuation of 7 GHz surface acoustic waves on silicon

We measured the attenuation of GHz frequency surface acoustic waves (SAWs) on the Si (001) surface using an optical pump-probe technique at temperatures between 300 and 600 K. SAWs are generated and detected by a 700 nm Al grating fabricated by nanoimprint lithography. The grating for SAW generation is separated from the grating for SAW detection by $\ensuremath{\approx}150\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{m}$. The amplitude of SAWs is attenuated by coupling to bulk waves created by the Al grating, diffraction due to the finite size of the source, and the intrinsic relaxational Akhiezer damping of elastic waves in Si. Thermal phonon relaxation time and Gr\"uneisen parameters are fitted using temperature-dependent measurement. The $fQ$ product of a hypothetical micromechanical oscillator limited by Akhiezer damping at this frequency is $\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{13}$ Hz.

Determination of VOCs in the Indoor Air of a New and a Renovated Apartment

Abstract This study deals with the occurrence of volatile organic compounds (VOCs) in the indoor environment of a new and a renovated apartment. Qualitative determination of VOCs was carried out with a gas chromatograph with surface acoustic wave detector (GC/SAW). Concentrations of total volatile organic compounds (TVOC) were determined by a photoionization detector with UV lamp. Simultaneously, temperature and relative humidity were monitored with a data logger. The aim of this study was to determine of TVOC concentrations, to use of GC/SAW for determination of individual VOCs in indoor air as well as to predict possible sources of VOCs in these apartments. Measurements were performed after each construction work for better resolution of the contributions of individual materials to the levels of VOC. Mean concentrations of TVOC were 624 μg/m3 in the renovated apartment and 1,686 μg/m3 in the new apartment after completion of all works. The results from the renovated apartment showed that the use of new materials can lead to lower levels of organic compounds in indoor air compared to old materials that were less environmentally friendly. Many types of VOCs were found in both apartments. After reviewing the possible sources, it seems that the main sources of these substances were applied coatings and flooring materials.

Detection of third-hand smoke on clothing fibers with a surface acoustic wave gas sensor.

Third-hand smoke (THS) is a new cigarette-related issue defined as the residual contamination from cigarette smoke after a cigarette is extinguished. To detect THS on three commonly used clothing fibers-wool, cotton, and polyester, we applied two methods to measure the adsorption of THS: one was the gain of mass with an analytical balance after exposure to cigarette smoke; and the other was to detect the THS chemical compounds such as nicotine and 3-ethenylpyridine with a surface acoustic wave (SAW) sensor composed of coated oxidized hollow mesoporous carbon nanospheres. In the mass measurement, the gain of mass decreased in the order wool, cotton, and polyester; the latter gain was about one tenth that of wool. In the SAW detection, the frequency shift decreased in the same order-wool, cotton, and polyester. The residence period of THS on natural fiber (wool and cotton) is greater than on synthetic polyester fiber. These two tests provide quantitative results of THS on varied clothing fibers, to assess their risk after exposure to cigarette smoke.

Determination of elastic and thermal properties of a thin nanocrystalline diamond coating using all-optical methods

Results are presented on the thermal and elastic properties of a thin, 1.5μm, nanocrystalline diamond coating (NCD), deposited on a silicon substrate by microwave plasma enhanced chemical vapor deposition. A combination of two all-optical measurement techniques, impulsive stimulated thermal scattering and grating induced laser beam deflection, was employed to launch and detect surface acoustic waves (SAWs). The relation between the dispersive propagation velocity of SAWs to the coating-substrate geometry is exploited to determine the elastic properties of the NCD coating. The elastic properties are found to be consistent with literature values. The thermal properties of the coating were determined by monitoring the thermal diffusion induced washing away of the laser induced transient surface temperature grating. The transient thermal grating signals were fitted by the low-frequency limit of a thermoelastic model for a multilayer configuration. Similar to the dispersion of the surface acoustic wave velocity, the characteristic time of the thermal diffusion driven grating decay evolves from a coating-dominated value at short grating spacings towards a substrate-dominated value at grating spacings well exceeding the coating thickness. The grating spacing dependence of the corresponding effective thermal diffusivity was experimentally determined and fitted, leading to a value for the thermal diffusivity of the NCD coating αNCD=8.4−0.1+2.7mm2·s−1, which is an order of magnitude lower than that of the silicon substrate. The low value of the thermal diffusivity is interpreted with a simple touching model.

Measurement of VOCs with a Portable GC/SAW Detector

This paper describes the determination of the concentrations of volatile organic compounds (VOCs) in two Slovak buildings. Qualitative measurements were performed using an electronic nose, zNose® 4300. This device has been developed by Electronic Sensor Technology. Technology consists of a combination of gas chromatography with SAW (Surface Acoustic Wave) detector. This model was chosen for measurement because it provides a relatively fast results and full portability. Quantitative measurements were performed using a photoionization detector with UV lamp, ppbRAE 3000. Previous studies of indoor air in buildings showed that the occupant behaviour and consumer products influence indoor air quality, as well as building structures and location of the house. Our measurements were focused on VOCs, which are currently an important group of chemical pollutants. Term VOCs includes a wide range of hydrocarbons possessing a characteristic ability to vaporize at room temperature. VOCs are emitted from a large range of well-known sources. For example, from building materials, household products, human activities, cleaning, smoking, or industrial emissions, exhaust from vehicles are some of the anthropogenic sources of VOCs in the outdoor environment which contribute to indoor VOCs. Increased attention is also given to them because they can have a negative impact on human health. This study was carried out on the basis of complaints (smell, headache, nausea) of a laboratory worker, who has an office in the model house. Thus, the aim of this work was to determine what substances cause referred complaints and their possible sources.

Bi‐channel Surface Acoustic Wave Gas Sensor for Carbon Disulfide and Methanol Vapors in Polymer Plants

AbstractA C60‐polyphenylacetylene (C60‐PPA) and polyvinylpyrrolidone (PVP) coated two‐channel surface acoustic wave (SAW) crystal gas sensor with a homemade computer interface for data acquisition and data processing was developed and employed to detect carbon disulfide (CS2) and methanol (CH3OH) vapors in polymer plants. The frequency of surface acoustic wave oscillator decreases due to the adsorption of gas molecules on the coated materials of the SAW sensor. Six coating materials (C60‐PPA, nafion, PPA, crytand [2,2], polyethene glycol and PVP) were used to adsorb and detect carbon disulfide and methanol gases. Adsorption of all the six coating materials to CS2 and CH3OH was found to be physical adsorption. The C60‐PPA coated SAW detector exhibited more sensitive to CS2 than the other coating materials. In contrast, the PVP coated SAW detector was more sensitive to CH3OH than the other coating materials. With the two‐channel SAW sensor, the C60‐PPA coated SAW showed a good detection limit of 0.4 ppm and good reproducibility with RSD of 3.37 % (n=10) for CS2. Similarly, the PVP coated SAW also showed a good detection limit of 0.05 ppm and good reproducibility, with RSD of 0.86 % (n=10) for CH3OH. The interference effect of other organic molecules on the SAW detection system was negligible, except for the irreversible adsorption of C60‐PPA to propylamine. The frequency signals from the two‐channel SAW sensor array C60‐PPA and PVP coatings were processed by a back‐propagation artificial neural network (BPN) and multiple regression analysis (MRA). Thus a two‐channel SAW sensor array with BPN and MRA has been successfully applied for the qualitative and quantitative analyses of CS2 and CH3OH in mixtures.

Surface-acoustic-wave-driven ferromagnetic resonance in (Ga,Mn)(As,P) epilayers

Interdigitated transducers were used to generate and detect surface acoustic waves on a thin layer of (Ga,Mn)(As,P). The out-of-plane uniaxial magnetic anisotropy of this dilute magnetic semiconductor is very sensitive to the strain of the layer, making it an ideal test material for the dynamic control of magnetization via magneto-striction. The time-domain measurement of the amplitude and phase of the transmitted SAW during magnetic field sweeps indicated a clear resonant behavior at a field close to the one calculated to give a precession frequency equal to the SAW frequency. A resonance was observed from 5K to 85K, just below the Curie temperature of the layer. A full analytical treatment of the coupled magnetization/acoustic dynamics showed that the magneto-strictive coupling modifies the elastic constants of the material and accordingly the wave-vector solution to the elastic wave equation. The shape and position of the resonance were well reproduced by the calculations, in particular the fact that velocity (phase) variations resonated at lower fields than the acoustic attenuation variations.

Determination of elastic properties of a MnO2 coating by surface acoustic wave velocity dispersion analysis

MnO2 is a material of interest in the development of high energy-density batteries, specifically as a coating material for internal 3D structures, thus ensuring rapid energy deployment. Its electrochemical properties have been mapped extensively, but there are, to the best of the authors' knowledge, no records of the elastic properties of thin film MnO2. Impulsive stimulated thermal scattering (ISTS), also known as the heterodyne diffraction or transient grating technique, was used to determine the Young's modulus (E) and porosity (ψ) of a 500 nm thick MnO2 coating on a Si(001) substrate. ISTS is an all optical method that is able to excite and detect surface acoustic waves (SAWs) on opaque samples. From the measured SAW velocity dispersion, the Young's modulus and porosity were determined to be E = 25 ± 1 GPa and ψ=42±1%, respectively. These values were confirmed by independent techniques and determined by a most-squares analysis of the carefully fitted SAW velocity dispersion. This study demonstrates the ability of the presented technique to determine the elastic parameters of a thin, porous film on an anisotropic substrate.

Rapid Point-Of-Care Breath Test for Biomarkers of Breast Cancer and Abnormal Mammograms

BackgroundPrevious studies have reported volatile organic compounds (VOCs) in breath as biomarkers of breast cancer and abnormal mammograms, apparently resulting from increased oxidative stress and cytochrome p450 induction. We evaluated a six-minute point-of-care breath test for VOC biomarkers in women screened for breast cancer at centers in the USA and the Netherlands.Methods244 women had a screening mammogram (93/37 normal/abnormal) or a breast biopsy (cancer/no cancer 35/79). A mobile point-of-care system collected and concentrated breath and air VOCs for analysis with gas chromatography and surface acoustic wave detection. Chromatograms were segmented into a time series of alveolar gradients (breath minus room air). Segmental alveolar gradients were ranked as candidate biomarkers by C-statistic value (area under curve [AUC] of receiver operating characteristic [ROC] curve). Multivariate predictive algorithms were constructed employing significant biomarkers identified with multiple Monte Carlo simulations and cross validated with a leave-one-out (LOO) procedure.ResultsPerformance of breath biomarker algorithms was determined in three groups: breast cancer on biopsy versus normal screening mammograms (81.8% sensitivity, 70.0% specificity, accuracy 79% (73% on LOO) [C-statistic value], negative predictive value 99.9%); normal versus abnormal screening mammograms (86.5% sensitivity, 66.7% specificity, accuracy 83%, 62% on LOO); and cancer versus no cancer on breast biopsy (75.8% sensitivity, 74.0% specificity, accuracy 78%, 67% on LOO).ConclusionsA pilot study of a six-minute point-of-care breath test for volatile biomarkers accurately identified women with breast cancer and with abnormal mammograms. Breath testing could potentially reduce the number of needless mammograms without loss of diagnostic sensitivity.

Influence of acoustic leakage at fluid–solid interface on interferometric detection of surface acoustic wave

When using laser interferometer to detect surface acoustic wave at fluid–solid interface, there are two factors which will cause the optical path length variation of the probe laser beam: interface deformation, and refractive index changes in fluid induced by acoustic leakage. Influence of acoustic leakage on laser interferometric detection for surface acoustic wave is researched here. A metal plate immersed in an infinite fluid is used as a physical model. Interface deformation due to laser-induced acoustic wave and pressure in fluid due to acoustic leakage are computed for select cases by finite element method. The optical path length variation caused by the two factors are calculated respectively and compared. The results show that the influence of acoustic leakage increases with the increasing acoustic impedance matching of fluid and solid, the peak-to-peak of influence degree increases linearly with the increasing acoustic impedance of fluid, and that decreasing the distance between the interferometer and interface can effectively reduce the influence of acoustic leakage.

Surface acoustic wave generation and detection using graphene interdigitated transducers on lithium niobate

We demonstrate the feasibility of using graphene as a conductive electrode for the generation and detection of surface acoustic waves at 100 s of MHz on a lithium niobate substrate. The graphene interdigitated transducers (IDTs) show sensitivity to doping and temperature, and the characteristics of the IDTs are discussed in the context of a lossy transmission line model.

Circuit Design of Surface Acoustic Wave Based Micro Force Sensor

Pressure sensors are commonly used in industrial production and mechanical system. However, resistance strain, piezoresistive sensor, and ceramic capacitive pressure sensors possess limitations, especially in micro force measurement. A surface acoustic wave (SAW) based micro force sensor is designed in this paper, which is based on the theories of wavelet transform, SAW detection, and pierce oscillator circuits. Using lithium niobate as the basal material, a mathematical model is established to analyze the frequency, and a peripheral circuit is designed to measure the micro force. The SAW based micro force sensor is tested to show the reasonable design of detection circuit and the stability of frequency and amplitude.

Feasibility Study on Noncontact Monitoring of Temperature Distributions of Rotating Tool

In the fields of materials science and engineering, measuring temperature has become one of the most fundamental and important issues. In particular, there are growing demands for monitoring temperature gradient and its transient variation of materials being processed at higher temperatures because the temperature state during processing crucially influences the quality of final products. Such temperature monitoring is also required for rotating machining processes such as tuning, milling and friction stir welding (FSW). In this work, a new noncontact method for monitoring temperature distribution of a heated rotating cylindrical object is presented. A laser-ultrasonic technique is employed in the method. Surface temperature measurements for the cylindrical object using the laser-ultrasonic technique and heat conduction analyses are combined together for making quantitative evaluation of temperature distribution in the radial direction of the cylindrical object. To demonstrate the feasibility of this method, an experiment with a steel cylinder of 100 mm in diameter rotating at 300 min-1 and heated up to 100 °C on the surface is carried out. A pulsed laser generator and a laser Doppler vibrometer are used for generating and detecting surface acoustic waves (SAWs) on the steel cylinder, respectively. Measured SAWs are used for determining both surface and internal temperatures of the cylinder. As a result, the estimated temperature distributions during heating almost agree with those measured by an infrared radiation camera.

Laser-Generated Surface Acoustic Wave Technique for Crack Monitoring – A Review

In this paper, the principle of surface acoustic wave techniques and their application to the monitoring of cracks are presented and compared to other classic non-destructive techniques. A practical classification of methods regarding the excitation and detection of surface acoustic waves is enumerated, among them, laser-generated surface acoustic wave technique is carefully analyzed as a prospective technique, and two important detection methods using piezoelectric and light deflection are described. Then, the strategies and variables used in crack monitoring based on laser-generated surface acoustic wave technique are reviewed. To achieve the goal of quantitative detection of cracks, most researchers use numerical models and experiments to characterize main crack features. Discussions and prospective approaches for further quantitative monitoring of cracks are provided.

Ultrasensitive Surface Acoustic Wave Detection of Collective Plasmonic Heating by Close-Packed Colloidal Gold Nanoparticles Arrays

A novel electrical detection method based on surface acoustic wave (SAW) is introduced to investigate the heat generation from a two-dimensional (2D) or three-dimensional (3D) close-packed gold nanoparticle (AuNP) array exhibiting tunable collective surface plasmon resonance (CSPR). We have found that the SAW sensor can detect the CSPR-induced photothermal heating effect. The conversion of absorbed light around the CSPR frequency into heat and subsequent transfer from the AuNP array to the lithium niobate (LiNbO3) substrate allows a dual delay-line SAW system to dynamically measure the resonant frequency change of the SAW oscillator coated with a 2D or 3D AuNP array. The experimental findings indicate that SAW detection provides an ultrasensitive (detection limit of temperature change <1 × 10–3 °C) electrical readout scheme for measuring the collective plasmonic heating of close-packed AuNP arrays with a linear dynamic range of incident light intensity and a designable CSPR spectral response.

A Four-Quadrant PVDF Transducer for Surface Acoustic Wave Detection

In this paper, a polyvinylidene fluoride (PVDF) piezoelectric transducer was developed to detect laser-induced surface acoustic waves in a SiO2-thin film–Si-substrate structure. In order to solve the problems related to, firstly, the position of the probe, and secondly, the fact that signals at different points cannot be detected simultaneously during the detection process, a four-quadrant surface acoustic wave PVDF transducer was designed and constructed for the purpose of detecting surface acoustic waves excited by a pulse laser line source. The experimental results of the four-quadrant piezoelectric detection in comparison with the commercial nanoindentation technology were consistent, the relative error is 0.56%, and the system eliminates the piezoelectric surface wave detection direction deviation errors, improves the accuracy of the testing system by 1.30%, achieving the acquisition at the same time at different testing positions of the sample.

Point-of-care breath test for biomarkers of active pulmonary tuberculosis

Volatile organic compounds (VOCs) in breath provide biomarkers of tuberculosis (TB) because Mycobacterium tuberculosis manufactures VOC metabolites that are detectable in the breath of infected patients. We evaluated breath VOC biomarkers in subjects with active pulmonary TB, using an internet-linked rapid point-of-care breath test. 279 subjects were studied at four centers in three countries, Philippines, UK, and India, and data was analyzed from 251 (130 active pulmonary TB, 121 controls). A point-of-care system collected and concentrated breath and air VOCs, and analyzed them with automated thermal desorption, gas chromatography, and surface acoustic wave detection. A breath test was completed in 6 min. Chromatograms were converted to a series of Kovats Index (KI) windows, and biomarkers of active pulmonary TB were identified by Monte Carlo analysis of KI window alveolar gradients (abundance in breath minus abundance in room air). Multiple Monte Carlo simulations identified eight KI windows as biomarkers with better than random performance. Four KI windows corresponded with KI values of VOCs previously identified as biomarkers of pulmonary TB and metabolic products of M. tuberculosis, principally derivatives of naphthalene, benzene and alkanes. A multivariate predictive algorithm identified active pulmonary TB with 80% accuracy (area under curve of receiver operating characteristic curve), sensitivity=71.2%, and specificity = 72%. Accuracy increased to 84% in age-matched subgroups. In a population with 5% prevalence, the breath test would identify active pulmonary TB with 98% negative predictive value and 13% positive predictive value. A six-minute point-of-care breath test for volatile biomarkers accurately identified subjects with active pulmonary TB.